Originally Posted by edwmax
Thanks Louis, I have those marks on some of my plants too. But haven't identified them as being cause by thrips. I'm not sure if I know what a thrip looks like. I just see the black marks. ... Anyway I find that copper sulfate (& lime) will also work as a pesticide on these vary small insects/grubs due to copper toxicity and well used by by organic gardeners. ... And it is very economical to mix. ... So copper sulfate can be used as an algaecide, bactericide, fungicide, antimicrobial and molluscicide for host of gardening/Ag problems.
Thrips are invisible to the naked eye, the marks on the pstem are not such a big problem but if untreated, they will bore hundreds of holes in the skin of the fruit, lowering the value and a cause of bursting through weakening of the skin. I assume the holes on the leaves could also be caused by thrips. This problem creeps up in the rainy season her, and requires regular treatment as the rain will wash away the coating. Thrips are causing a big problem for organic banana growers in Costa Rica for who have often had to give up the organic label for lack of a working acceptable treatment that works.